1. Field of the Invention
The invention is a device/system and method for the percutaneous treatment of veins. In particular, the device and method are directed at the destruction of veins by endovenously irradiating abnormal or diseased veins with wavelengths at about 980 nm and about 1460 nm, in combination, or with the latter alone, to affect destruction of the vein.
2. Invention Disclosure Statement
The present invention is a device and method for endovenous thermal treatment of diseased or abnormal veins; especially varicose veins. An increasing number of individuals are seeking treatment of lower extremity veins for symptomatic, as well as cosmetic concerns. The use of endovascular treatment enables proximal access to a vascular treatment site enabling use of a less harmful and less powerful laser, when compared to surface treatment lasers which are more powerful and cause damage to surrounding tissue and are not an effective treatment.
Veins are thin walled vessels containing many one way valves which open to allow the blood to flow in one direction and close to prevent back flow. These valves might grow weak or malfunction which increases the blood volume in the vessels causing the vessel walls to dilate or enlarge due to the pressure exerted on the walls. Varicose veins is a common medical condition among adults with symptoms such as swelling, aching, itching and discomfort in the legs with cosmetic deformities visible in many cases. If left untreated varicose veins can cause many medical complications.
The use of lasers in the treatment of various vascular diseases, such as facial telangiectasias and some lower extremity veins externally has been achieved with some success. In this technique laser energy is irradiated on the surface of the skin which on penetration is absorbed by the blood which coagulates and collapses the blood vessel. Larger varicose veins located in deeper soft tissue cannot be treated with this method as higher powers are required. This could also lead to side effects including scarring and skin pigmentation changes.
Various forms of treatment are present, for temporary relief such as the use of compression stockings or elevating the effected area is common. Common long term treatments for varicose veins include sclerotherapy, ambulatory phlebectomy, ligation and stripping of the greater saphenous vein in cases of sapheno-femoral junction incompetence. Sclerotherapy involves introduction of a chemical irritant into the vein. The chemical acts on the vein walls causing the walls to occlude and block the blood flow. Complications can be severe causing skin ulceration, skin reactions and permanent staining. Treatment is also limited to certain vein size ranges and there is relatively high recurrence rate due to vessel recanalization. Surgical excision requires the use of anesthetic and involves long recovery periods. Even though it has a high success rate it is an expensive process and complications from surgery can arise. Surgical excision also leaves behind permanent scarring and deformities on treated areas. Ambulatory phlebectomy involves use of multiple incisions through the skin along the length of the vein to remove the vein. The process is relatively lengthy, expensive and leaves behind visible scars on the tissue.
One other technique used to treat varicose veins is RF energy which delivers electrical heat directly to the vessel wall; this technique has a more uniform application of energy along the vessel walls. But the catheters used are expensive and complicated; also the catheter heats up inside the vein and indiscriminately causes surrounding tissue damage in many cases. Because diode lasers use a small fiber and because the heat remains inside the vessel, smaller vessels on the surface of skin can be treated. This cannot be done using the radio frequency technique.
Endovascular laser therapy is a relatively new technique for venous reflux disease. In this technique an optical fiber is percutaneously inserted into the vein to be treated. Laser energy is then radiated through the bare fiber tip into the vessel. The energy contacts the contents of the vein causing the vein to occlude or collapse. The laser is slowly withdrawn along the entire segment of the vein to be treated.
Prior techniques to treat varicose veins have attempted to heat the vessel wall by targeting the hemoglobin in the blood and then having the heat transfer to the wall. The wavelength ranges from 500 nm to 1100 nm and scatters in tissue compared to other wavelengths. These wavelengths penetrate to varied depths unless stopped by an absorbing media. The wavelength ranges from 500 nm to 1100 nm could cause damage to surrounding tissue if the power levels are not within safe limits. The blood in veins absorbs these wavelength energies in less than 1 mm in the presence of hemoglobin. This causes blood to heat up quickly and damage the vein wall by conduction and not by direct wall absorption. These wavelength ranges are however good for the absorption of blood as seen by the absorption peaks of Hemoglobin and Oxy-hemoglobin around the 980 nm wavelength, but will not occlude the vein walls by conduction of this heat from the blood to the vein walls as this requires use of higher powers and longer pulse durations at a particular site. The higher wavelengths have a much higher water and collagen absorption in vein walls as seen in absorption peaks around the 1460 nm wavelength.
In Publication U.S. 2004/0092913 by Hennings et al., a device and method are given for the treatment of varicose veins or the greater saphenous vein. The device includes a laser of 1320 nm wavelength used for treatment to occlude and reabsorb the vein. The fiber optic catheter may have a frosted or diffusing tip catheter, a motorized pull back device and thermal sensor to track temperature in vessel. This technique requires drainage of blood before lasing to effectively occlude the vein walls. The energy absorbed by blood in this wavelength range is relatively low hence effective absorption of blood in this range is not observed. This could lead to improper or incomplete treatment in the treated vein if blood is present. Also the use of cooling mechanism is seen which indicates use of higher energy to provide a means to minimize surrounding tissue damage. The use of higher energies or longer durations of exposure at a site results in damage to peripheral veins and surrounding tissue.
In U.S. Pat. No. 6,398,777 by Navarro et al., describes use of laser energy wavelengths from about 532 nm to about 1064 nm for treating blood vessels. This technique requires application of pressure over the laser tip and emptying of the vessel of blood to ensure contact between the vessel wall and fiber tip at the start and throughout the treatment. This necessity can result in vessel perforation and force blood into surrounding tissue or veins causing discomfort and bruising. The laser energy directed at the contact point causes perforations in the wall and surrounding area, directly or indirectly These wavelength ranges require a cooling mechanism to minimize burning caused by transmitted energy.
In U.S. Pat. No. 5,531,739 by Trellas and U.S. Pat. No. 5,578,029 by Trellas et al., a device to perform under skin laser treatment is described. The treatment is limited to depths that are specifically used for different treatments. The treatment necessitates multiple insertions along the length of treatment vein for effective occlusion along the length. The technique is cumbersome and expensive as specialized tips are needed. The laser energy is delivered to the vicinity of the vein which causes closure of the vein by collapsing its wall which is an indirect solution. By the introduction of multiple punctures in the skin the risk of infection is increased. The use of near vein radiation also might cause disfiguration of the skin surface and damage to surrounding tissue. Since treatment is near a vein the radiation is also applied to nerves which can be painful to the patient.
In prior art, usage of 10 to about 20 W is required because the laser wavelengths are not effectively coupled to the vessel walls, are absorbed by the blood or are transmitted through the vessel walls. In such cases external cooling devices are necessary to prevent burns on the skin surface. In some cases the fiber tips need to be conditioned in order to provide satisfactory results because of the way these laser wavelengths interact with water and tissue. By trapping heat in the fiber tip, the “hot tip” can reach temperature exceeding 400° C. Also the energy from these lasers is absorbed by the conditioned tips and not in water, hemoglobin or tissue. Conductive heat transfer can damage collateral tissue causing swelling, tissue necrosis, charring and patient discomfort.
A need exists for an endovascular percutaneous laser treatment device/system and method for the treatment of varicose veins with capability for the surgeon or operator to select an optimum combination of wavelengths for absorption in hemoglobin and water in order to produce direct endothelial and vein wall damage with subsequent fibrosis, without incurring the problems and deleterious side effects associated with the prior art.